Simulation of hole intersubband scattering, transport, and luminescence in p-GaAs/AlGaAs quantum cascade structures

Intersubband transitions within the conduction band in semiconductor quantum wells have been widely explored, which eventually led to their application in quantum well infrared photodetectors and quantum cascade lasers (QCLs). There have been considerably fewer studies of hole intersubband transitions, which are more complicated than their electronic counterparts. They are very interesting, however, because of optical activity for both TM and TE light polarization, offering the possibility of both edge and surface-normal emission or absorption. Earlier studies have mostly focused on bound-continuum transitions in GaAs/AlGaAs and Si/SiGe systems for infrared detection. The interest in hole intersubband transitions has been recently renewed in view of their application for mid- and far-infrared emitters, including QCLs. Considerable progress has been made in the design and realization of p-doped Si/SiGe quantum cascades and luminescence has been obtained in the THz [1] and mid-infrared [2] range, although laser action has yet to be demonstrated.